Acoustic panels are utilized to change the acoustic qualities of a space, such as a room, studio, theater, stadium, etc. A wide variety of acoustic-affecting materials, such as acoustic absorbers are employed. A conventional acoustic panel 10, commonly used in recording studios, home theaters, concert halls, churches, offices, factories, etc., to reduce the amount of reverberant (reflected) sound energy and thereby improve the recording and/or listening environment, is illustrated in FIG. 1. The illustrated acoustic panel 10 has a main body portion 12 with a front face 14 and an opposite rear face 16. The front face 14 has an irregular or convoluted shape and is the surface that is designed to face a sound source within a space, such as a musical instrument within a room in which the acoustic panel 10 is being used. The rear surface 16 has a planar configuration that facilitates mounting the acoustic panel 10 to a wall or ceiling. Advantages of conventional acoustic panels with convoluted surfaces, such as illustrated in FIG. 1, include weight reduction and improved random incidence sound absorption performance.
It is known that improved sound absorption performance can be achieved by applying a semi-permeable, airflow-resistive facing to the planar surface of a conventional non-convoluted acoustic panel that is exposed to a sound source. For planar sound absorber surfaces, lamination of such a facing material to the acoustic panel is typically achieved using conventional adhesive systems or bonding technologies. The improvements in sound absorption performance for these planar, non-convoluted panels can range up to 100% or more at some frequencies. Unfortunately, it is not practical to attach a facing layer of material to acoustic panel surfaces with irregular or convoluted shapes, such as the front surface 14 of the acoustic panel 10 illustrated in FIG. 1.
In addition, it is known that an airflow-resistive facing applied to the rear planar surface of a conventional acoustic panel, such as the rear surface 16 of the acoustic panel 10 illustrated in FIG. 1, wherein the airflow-resistive facing is positioned against a mounting surface, such as a wall or ceiling, is ineffective in improving sound absorption performance because of the close proximity of the facing to an impermeable reflective surface. The close proximity inhibits the oscillatory flow of sound pressure waves through the facing, which in turn limits the viscous loss of acoustical energy by this action. As such, conventional acoustic panels with a convoluted surface do not incorporate airflow-resistive materials to either side thereof.